sandbox/amk/abc/abc.py

   1 """abc.py
   2
   3 Implements a 'music' directive that accepts musical passages written
   4 in ABC notation.  Requires that abcm2ps and Ghostscript be installed.
   5
   6 .. music::
   7
   8     % Sample file to test various features of abc2ps
   9     X:1
  10     T:Scale
  11     M:C
  12     K: clef=bass
  13      "C,"C,"D,"D,
  14
  15 """
  16
  17 import os, sys, tempfile, popen2
  18
  19 from docutils import nodes
  20 from docutils.parsers.rst.directives import register_directive
  21
  22 music_counter = 1
  23
  24 def ABCDirective (name, arguments, options, content, lineno,
  25                   content_offset, block_text, state, state_machine):
  26     abc_temp = tempfile.NamedTemporaryFile("wt")
  27     abc_temp.write("\n".join(content))
  28     abc_temp.flush()
  29     fd, ps_temp = tempfile.mkstemp()
  30     global music_counter
  31     output_path = state.document.settings._destination or '.'
  32     output_name = os.path.join(output_path, 'music-%i.png' % music_counter)
  33     music_counter += 1
  34     sts1 = sts2 = sts3 = 0
  35     pipe = popen2.Popen3('abcm2ps -O/dev/stdout - < %s > %s'
  36                          % (abc_temp.name, ps_temp),
  37                          capturestderr=True
  38                          )
  39     pipe.tochild.close()
  40     pipe.fromchild.read()
  41     errors = pipe.childerr.read()
  42     errors = parse_errors(errors, lineno)
  43     sts1 = pipe.wait()
  44     if sts1 == 0:
  45         sts2 = os.system('gs -q -sOutputFile=%s -sDEVICE=pngmono - <%s'
  46                     % (output_name, ps_temp))
  47     if sts2 == 0:
  48         sts3 = os.system('gs -q -sOutputFile=%s -sDEVICE=pngmono - <%s'
  49                     % (output_name, ps_temp))
  50     try:
  51         os.unlink(ps_temp)
  52     except os.error:
  53         pass
  54
  55     abc_temp.close()
  56     if sts1 != 0 or sts2 != 0:
  57         error = state_machine.reporter.error(
  58                   'Error processing music directive:\n\t' +
  59                   ('\n\t'.join(errors)),
  60                   nodes.literal_block(block_text, block_text),
  61                   line=lineno)
  62         return [error]
  63     else:
  64         # Crop excess whitespace from the image
  65         crop_image(output_name)
  66
  67         # Return an image directive.
  68         options['uri'] = os.path.basename(output_name)
  69         return [nodes.image(output_name, **options)]
  70
  71 import re
  72 error_pat = re.compile('(in line )(\d+)')
  73 def parse_errors (errors, line_start):
  74     lines = errors.split('\n')
  75     lines =  [ line for line in lines if line.startswith('Error')]
  76     def f (m):
  77         return m.group(1) + str(line_start+int(m.group(2)))
  78     lines = [ error_pat.sub(f, line) for line in lines]
  79     return lines
  80
  81
  82 def crop_image (filename):
  83     """Reads the image specified by filename, crops excess space off it,
  84     and writes it out to the same file."""
  85     from PIL import Image
  86     image = Image.open(filename)
  87     for edge in 'NSWE':
  88         image = _crop(image, edge)
  89     image.save(filename)
  90
  91 def _crop (image, edge):
  92     im_x, im_y = image.size
  93     if edge == 'N':
  94         start = (0,0)
  95         scan_increment = (1,0)
  96         line_increment = (0,1)
  97     elif edge == 'S':
  98         start = (0,im_y-1)
  99         scan_increment = (1,0)
 100         line_increment = (0,-1)
 101     elif edge == 'E':
 102         start = (im_x-1,0)
 103         scan_increment = (0,1)
 104         line_increment = (-1,0)
 105     elif edge == 'W':
 106         start = (0,0)
 107         scan_increment = (0,1)
 108         line_increment = (1,0)
 109
 110     # Look for blank lines
 111     def is_white (color):
 112         return color == 255
 113
 114     def is_blank (x,y):
 115         x_inc, y_inc = scan_increment
 116         while 0 <= x < im_x and 0 <= y < im_y:
 117             point = image.getpixel((x,y))
 118             if not is_white(point):
 119                 return False
 120             x += x_inc
 121             y += y_inc
 122         return True
 123
 124     # Look for blank edges, jumping in increments of JUMP pixels.
 125     JUMP = 5
 126     x, y = start
 127     x_inc, y_inc = line_increment
 128     while is_blank(x,y):
 129         x += x_inc * JUMP
 130         y += y_inc * JUMP
 131
 132     # Found a non-blank line, so scan back
 133     x -= x_inc
 134     y -= y_inc
 135     while not is_blank(x,y):
 136         x -= x_inc
 137         y -= y_inc
 138
 139     # OK; x,y are now on the first blank line, so crop it
 140     if edge == 'N':
 141         box = (0,y, im_x, im_y)
 142     elif edge == 'S':
 143         box = (0,0, im_x, y)
 144     elif edge == 'E':
 145         box = (0,0, x, im_y)
 146     elif edge == 'W':
 147         box = (x,0, im_x, im_y)
 148
 149     image = image.crop(box)
 150     image.load()
 151     return image
 152
 153
 154 ABCDirective.content = True
 155
 156 def register():
 157     register_directive('music', ABCDirective)